Jekyll select current page url and change its class

I've been using Jekyll for a static site (so that its easy to maintain), and have been stuck at the following feature :

This is my link bar :

<ul id="links">
    <li class="first"><a class="active" href="/">Home</a></li>
    <li><a href="./associate.html">Associate With Us</a></li>
    <li><a href="./media.html">Media</a></li>
    <li><a href="./clients.html">Clients</a></li>
    <li class="last"><a  href="./contact.html">Contact Us</a></li>
</ul>       

The active class handles the coloring. What I want is this class be applied by jekyll depending on some variable set using liquid/YAML.

Is there some easy way to go about this?

Since the bar is common to all the pages, it is now in the default layout. I could go around by using Javascript to detect the url, and do the highlighting but was wondering if there was any way of doing this in Jekyll.

I do this in two pages I have set up in Jekyll.

The first thing I do is creating an entry inside _config.yml with the information of all the pages:

# this goes inside _config.yml. Change as required
navigation:
- text: What we do
  url: /en/what-we-do/
- text: Who we are
  url: /en/who-we-are/
- text: Projects
  url: /en/projects/
  layout: project
- text: Blog
  url: /en/blog/
  layout: post

Then, on my main layout, I use that information to generate the navigation links. On each link, I compare the url of the link with the url of the current page. If they are equal, the page is active. Otherwise, they are not.

There's a couple special cases: all blog posts must highlight the "blog" link, and the front pages (English and Spanish) must not present the nav bar. For both cases, I rely on the fact that blog posts and front pages have specific layouts (notice that the "Blog" and "Project" links on the yaml have an extra parameter called "layout")

The navigation code is generated like this:

{% unless page.layout == 'front' %}
  <ul class="navigation">
    {% for link in site.navigation %}
      {% assign current = nil %}
      {% if page.url == link.url or page.layout == link.layout %}
        {% assign current = 'current' %}
      {% endif %}

      <li class="{% if forloop.first %}first{% endif %} {{ current }} {% if forloop.last %}last{% endif %}">
        <a class="{{ current }}" href="{{ link.url }}">{{ link.text }}</a>
      </li>
    {% endfor %}
  </ul>
{% endunless %}

I still have to remember adding an entry to _config.yaml every time I add a new page, and then restart Jekyll, but it happens very infrequently now.

I think the navigation yaml could go inside an _include called "navigation" or something similar, but I haven't tried using yaml inside those so I don't know whether it will work. In my case, since I've got a multi-lingual site, it's easier to have everything inside config (missing translations are easier to spot)

I hope this helps.

As a further extension on the work of the other, here is a way to make it work without soggy index.html showing on all your beautiful URLs:

---
navigation:
 - text: Home
   url: /
 - text: Blah
   url: /blah/
---
{% assign url = page.url|remove:'index.html' %}
{% for link in page.navigation %}
<li {% if url == link.url %}class="active"{% endif %}>
    <a href="{{link.url}}" title="{{link.title}}">{{link.text}}</a>
</li>
{% endfor %}

The gold is in the assign statement which gets the page URL (which naturally includes the index.html and then strips it off to match the page.navigation pretty URLs.

This may be a new feature since the question first appeared, but I've discovered this can all be done in one file:

1. define the navigation as a variable in the yaml header
2. loop over the variable using liquid

So in my _layouts/base.html I have:

---
navigation:
- text: Home
  url: /index.html
- text: Travel
  title: Letters home from abroad
  url: /travel.html
---

<ul>
    {% for link in page.navigation %}
    <li {% if page.url == link.url %}class="current"{% endif %}>
       <a href="{{link.url}}" title="{{link.title}}">{{link.text}}</a></li>
    {% endfor %}
</ul>

Which generates this on the Home page:

<ul>
    <li class="current"><a href="/index.html" title="">Home</a></li>
    <li><a href="/travel.html" title="Letters home from abroad">Travel</a></li>
</ul>

And this on the Travel page:

<ul>
    <li><a href="/index.html" title="">Home</a></li>
    <li class="current"><a href="/travel.html" title="Letters home from abroad">Travel</a></li>
</ul>

I needed something simple, this is what I did.

In my front matter I added a variable called active

e.g.

---
layout: generic
title:  About
active: about
---

I have a navigation include with the following section

    <ul class="nav navbar-nav">
        {% if page.active == "home" %}
            <li class="active"><a href="#">Home</a></li>
        {% else %}
            <li><a href="/">Home</a></li>
        {% endif %}
        {% if page.active == "blog" %}
            <li class="active"><a href="#">Blog</a></li>
        {% else %}
            <li><a href="../blog/">Blog</a></li>
        {% endif %}
        {% if page.active == "about" %}
            <li class="active"><a href="#">About</a></li>
        {% else %}
            <li><a href="../about">About</a></li>
        {% endif %}
    </ul>

This works for me as the amount of links in the navigation are very narrow.